This invention relates to valve actuating mechanisms. More particularly, the invention provides a valve actuating mechanism which is extremely fast acting and which uses little power to move the mechanism to a desired operating position.
Spring biased valve actuating mechanisms have been employed in the past. Many are complicated, and many require large amounts of power during operation. The present invention, on the other hand, provides a valve actuating mechanism which is relatively simple in construction, is extremely fast acting, and it draws very little power.
Briefly, a spring biased valve mechanism is advantageously utilized together with a cable which is coupled at one portion thereof to a movable valve member and which is wound at another portion thereof about a drum. The drum is driven, advantageously through the mechanism of a clutch by a motor. The motor winds the cable about the drum until the movable valve member has moved from a first position, toward which it is normally biased, to a second position. When the second position is reached, the motor is de-energized and the drum is maintained in that position by any number of techniques. A first technique is to maintain the drum in contact with a motor-driven element through the use of a clutch (typically a solenoid clutch). The motor assembly may include a brake mechanism which brakes the motor from moving unless the motor is energized. Thus, as soon as the motor is de-energized corresponding to the movable valve member being in the second position, and the clutch mechanism is operative to couple together the drum and the motor-driven element, the valve member is retained in its second valve position. If the solenoid clutch is de-energized, the valve member immediately moves under the action of the spring biasing to the first valve position. Under this arrangement, the only power consumed is when the motor moves the valve from its first to second position and by the solenoid clutch.
An alternative arrangement is to couple a motor-driven element to a cable winding drum only during the movement of the valve member from its first to its second position. When in its second position, a ratchet mechanism engaging ratchet teeth on the drum serves to maintain the drum in the second valve position. The ratchet mechanism may be solenoid actuated, typically with a solenoid energization maintaining a ratchet member against the ratchet teeth on the drum. When the solenoid is de-energized, the ratchet member moves away from the ratchet teeth, permitting the drum to move by virtue of the spring biasing of the valve member permitting the valve member to return immediately to its first valve position.
In both of these alternative arrangements, a power on condition has been used to maintain the drum in a position corresponding to the second valve member position. Just the opposite could be completed, for example, the ratchet mechanism could be moved away from the ratchet teeth on the drum when power is applied to a solenoid mechanism rather than removed therefrom. In this case, no power is consummed while the valve is in the second position.
Patents representative of the state of the prior art are as follows:
U.S. Pat. No. 1,056,124 issued Mar. 18, 1913 - Rorke PA1 U.s. pat. No. 1,284,197 issued Nov. 5, 1918 - Larner & Taylor PA1 U.s. pat. No. 2,044,277 issued Jan. 16, 1936 - Bukolt PA1 U.s. pat. No. 2,259,973 issued Oct. 21, 1941 - Firehammer PA1 U.s. pat. No. 2,538,787 issued Jan. 23, 1951 - Manhartsberger PA1 U.s. pat. No. 2,827,259 issued Mar. 18, 1958 - Kindt PA1 U.s. pat. No. 3,447,777 issued June 3, 1969 - Carlson PA1 U.s. pat. No. 3,743,241 issued July 3, 1973 - Nansel PA1 Gr. Britain Pat. No. 1,215,122 published Dec. 9, 1970
The invention will be more completely understood by reference to the following detailed description, to be read in conjunction with the appended drawings.